MasterBias and MasterSuperBias in PixInsight

[de0s]

Hello,

I have an Aitk460ex mono camera and I was imaging at -20C over the weekend. I didn't do any calibration frames except for the flats and thought I'll do the Bias (and maybe also the Darks) at work as I have a temperature chamber that I can use to cool the camera. Anyway, I made 300 Bias frames @ -20C and integrated them in PI then applyed the SuperBias process. Below is what I got after boosted AutoStretch in PI. Doesn't that look strange? 

[swag72]

I thought I'd try a superbias instead of a master bias and while I didn't get what you have shown, when stacked with both and compared statistically, the superbias made no difference at all........... So I've not bothered to use it since!

[de0s]

Thanks Sara for the answer. If you look closely also on the left side of the above pic (at the regular integrated bias) you would see the darker "lanes" separated by a lighter one (similar to what's seen on the SuperBias, but more faded). Is this "normal" or should the sensor show a more "uniform" image?

[de0s]

To be a bit more accurate, these are the Bias and SuperBias stretched with the same curve:

[andrewluck]

300 bias frames is probably at the level where SuperBias won't actually produce any improvement. It has most effect with fewer frames.

Bias frames always look horrible. As a general rule, the more expensive the camera, the worse they look . The thing is, once you've stacked a large number to reduce the random noise then you're left with the cameras bias signal, which will be the same for every image you take and thus, easily subtracted.

If you decide to use dark calibration frames then you must also bias subtract the flats.

Andrew